Pre-introductory clinical trials of Norplant implants: a comparison of seventeen countries' experience

This report summarizes the data collected in pre-introductory Norplant implants clinical trials in 17 countries in Latin America, Asia and Africa that were coordinated by either the Population Council or Family Health International (FHI) between 1984 and 1991. A total of 16,282 women between the ages of 18 and 40 years participated in the studies with semi-annual or annual follow-up visits for up to 5 years. Gross cumulative pregnancy rates were < 0.6 per 100 women in the first year and < 1.5 in the second year in all countries. Significant differences in cumulative 5-year pregnancy rates were observed between weight groups 40-49 and 50-59 kg and between 50-59 and 60-69 kg body weight but not between 60-69 kg and those > or = 70 kg. Total cumulative discontinuation rates after five years of Norplant implants use ranged from 35.8 to 60.0 per 100 women. Younger age and low parity were associated with a higher discontinuation rate. Cumulative discontinuation rates for menstrual reasons more than doubled between the end of the first year and second year of use in 13 of 17 countries. This analysis and one previous review provide the only comparison of Norplant contraceptive system study results across a wide diversity of countries; thus allowing an appreciation of the range of clinical experience with Norplant implants and the regional differences in that experience.